1. Field of the Invention
The present invention relates to an image processing apparatus, particularly to an image processing apparatus that outputs a document image while reducing a color of the document image.
2. Description of the Related Art
Conventionally, for example, Japanese Patent Publication Laid-Open No. 2004-7370 discloses an image processing apparatus having a function of reducing the color of the document. The image processing apparatus of Japanese Patent Publication Laid-Open No. 2004-7370 is a personal computer, in which the color of the document scanned with a scanner is reduced and the color-reduced document image is printed on recording paper with a printer. A hue to be retained is specified by clicking a document image displayed on a monitor, and pixels except for the specified color are converted into a monochrome color to achieve the color reduction. In addition, a hue included in a predetermined range can be retained, and hue outside of the range can be converted into a monochrome color.
Thus, according to this related art, only a specified or predetermined range of hue is retained. Therefore, there is a problem in that when color reduction is performed to a document image having a broad hue distribution, the color-reduced image has low hue contrast.